Nicholas Christie-Blick

Sedimentary Geology and Tectonics

Nicholas Christie-Blick Homepage

Research

Paradox of Low-Angle Normal Faulting

Representing perhaps the greatest paradox of tectonics, still to be resolved satisfactorily, is the mismatch between so-called low-angle normal faults, widely documented in regions of crustal extension such as the Basin and Range Province of the western U.S., the absence of firm seismological evidence for active slip along such faults, and rock mechanical arguments suggesting that such deformation is unlikely. Implied frictional coefficients are implausibly small in most examples. Recent research, in collaboration with Mark Anders and students, has focused on the re-evaluation of critical areas in the western U.S. in which the paradigm of low-angle normal faulting was established. The so-called Sevier Desert detachment, which underlies much of the Sevier Desert in western Utah, has been reinterpreted as an unconformity between Paleozoic carbonate rocks and Cenozoic terrigenous sediments and lacustrine evaporites. The new interpretation is based on the study of cuttings and cores from boreholes that intersect the surface, and from a thorough re-evaluation of subsurface geophysical data, including data that were not available at the time of publication of earlier papers favoring the detachment hypothesis. Research in the northern part of the Mormon Mountains, Nevada casts doubt on the rootedness of low-angle normal faults that for more than 20 years have underpinned the literature on this topic. Data in hand suggest that interpreted detachment faults are instead the product of superficial landsliding. The emergence of this very different view in the Mormon Mountains effectively reopens the issue of how crustal extension takes place in highly extended terranes, and indeed whether the magnitude of crustal extension across this particular part of the Basin and Range Province may have been substantially overestimated.

Recent research in the Death Valley region of eastern California has focused on re-examination of the most important individual piece of evidence for more than 400% crustal extension between the Cottonwood Mountains and Nopah Range: a succession of mixed coarse and fine clastic sedimentary rocks of distinctive provenance (Eagle Mountain Formation) interpreted to have accumulated in an alluvial fan and lacustrine setting, and to have been transported tectonically more than 80 km from its Cottonwood Mountains source. Pervasive channelization and upward fining at scales of <1 m to as much as 14 m, along with the presence of abundant trough cross-stratification, imply that the sediments accumulated in a fluvial to lacustrine environment. If this alternative interpretation is correct, these deposits provide no constraint on either the magnitude or direction of extension.

Recent Publications

Anders, M.H., and Christie-Blick, N., 1994. Is the Sevier Desert reflection of west-central Utah a normal fault?: Geology, v. 22, p. 771-774.

Anders, M.H., Christie-Blick, N., and Wills, S., 1995. Is the Sevier Desert reflection of west-central Utah a normal fault?: Reply: Geology, v. 23, p. 670.

Anders, M.H., Christie-Blick, N., and Wills, S., 1998. Extensional collapse along the Sevier Desert reflection, northern Sevier Desert basin, western United States: Comment: Geology, v. 26, p. 474.

Anders, M.H., Christie-Blick, N., Wills, S., and Krueger, S.W., 2001. Rock deformation studies in the Mineral Mountains and Sevier Desert of west-central Utah: Implications for upper crustal low-angle normal faulting: Geological Society of America Bulletin, v. 113, p. 895-907.

Anders, M.H., Walker, C.D., and Christie-Blick, N., 2004. Fault zone deformation: The key to what is a rooted detachment and what is not: Geological Society of America, Abstracts with Programs, v. 36, No. 5, p. 548.

Bender, A.A., 2000. Mechanisms of intracratonic and rift basin formation: Insights from Canning basin, northwest Australia: Columbia University, New York, Ph.D. dissertation.

Bender, A.A., Christie-Blick, N., and Karner, G., 2000. Mechanism of intracratonic basin formation: Insights from the Canning Basin, NW Australia: 31st International Geological Congress, Rio de Janeiro, Brazil, Abstracts, CD-ROM.

Driscoll, N.W., Hogg, J.R., Christie-Blick, N., and Karner, G.D., 1995. Extensional tectonics in the Jeanne d'Arc Basin, offshore Newfoundland: implications for the timing of break-up between Grand Banks and Iberia, in Scrutton, R.A., Stoker, M.S., Shimmield, G.B., and Tudhope, A.W., eds., The Tectonics, Sedimentation and Palaeoceanography of the North Atlantic Region: Geological Society of London Special Publication No. 90, p. 1-28.

Karner, G.D., Christie-Blick, N., and Bedregal, R.P., 2003. Late syn-rift regional subsidence across the West African and Brazilian continental margins: The role of lower plate ductile extension: 6th Petroleum Geology Conference, North West Europe and Global Perspectives, London, England.

Levy, M., and Christie-Blick, N., 1989. Pre-Mesozoic palinspastic reconstruction of the eastern Great Basin (western United States): Science, v. 245, p. 1454-1462.

Renik, B., and Christie-Blick, N., 2004. Reevaluation of Eagle Mountain Formation and implications for extreme extension across Death Valley region, CA: Geological Society of America, Abstracts with Programs, v. 36, No. 5, p. 23.

Walker, C.D., Anders, M.H., Nagel, T., and Christie-Blick, N., 2004. Using field evidence to distinguish between rooted and rootless detachment faults in the Mormon Mountains, southeastern Nevada: Geological Society of America, Abstracts with Programs, v. 36, No. 5, p. 548.

Wills, S., Anders, M.H., and Christie-Blick, N., 2005. Pattern of Mesozoic thrust surfaces and Tertiary normal faults in the Sevier Desert subsurface, west-central Utah: American Journal of Science, v. 305, p. 42-100.